When a pattern of a photoresist is formed by photolithography, if interference of lights reflected on the boundary between a photoresist layer and a substrate and on the surface of the photoresist layer occurs at the time of exposure, the dimensional accuracy of the pattern will be decreased. For the purpose of reducing the reflected light, a method of forming an antireflection film on the surface of the photoresist layer has been studied. The antireflection performance of the antireflection film is determined by the refractive index and the thickness of the antireflection film and the refractive index and the thickness of the photoresist layer at the wavelength of an aimed light source, and it is necessary that the refractive index of the antireflection film is low as compared with the refractive index of the photoresist layer.
In general, a composition to form the antireflection film comprises a surfactant (a), a water-soluble binder polymer (b) and an aqueous medium (c) as chief constituents, and for example, in the following Patent Documents 1, 2 and 3, a compound containing fluorine atoms is used as the surfactant (a) to reduce the refractive index of the film.
However, in recent years, influences of PFAS (perfluoroalkyl sulfonates) and PFAA (perfluoroalkyl acids) each having 7 or more carbon atoms, which have been used for a composition for an antireflection film, over the environment have been considered. There is a movement to establish a limit on their import and production in SNUR (Significant New Use Role, Mar. 11, 2002, etc.) issued by EPA (Environmental Protection Agency). Under these circumstances, a composition for an antireflection film using no PFAS nor PFAA having 7 or more carbon atoms has been strongly desired at present.
Under these circumstances, for example, the following Patent Documents 4 to 7 propose a coating composition for an antireflection film using a polymer containing fluorine atoms as the water-soluble binder polymer (b).    Patent Document 1: JP-A-5-188598    Patent Document 2: JP-A-7-160002    Patent Document 3: JP-A-8-305032    Patent Document 4: JP-A-8-44066    Patent Document 5: JP-A-9-325500    Patent Document 6: JP-A-11-124531    Patent Document 7: JP-A-2004-37887